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Organic light-emitting diodes employing efficient reverse intersystem crossing for triplet-to-singlet state conversion

Nature Photonics volume 6, pages 253–258 (2012)Cite this article

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Abstract

Light emission from organic light-emitting diodes that make use of fluorescent materials have an internal quantum efficiency that is typically limited to no more than 25% due to the creation of non-radiative triplet excited states. Here, we report the use of electron-donating and electron-accepting molecules that allow a very high reverse intersystem crossing of 86.5% between non-radiative triplet and radiative singlet excited states and thus a means of achieving enhanced electroluminescence. Organic light-emitting diodes made using m-MTDATA as the donor material and 3TPYMB as the acceptor material demonstrate that external quantum efficiencies as high as 5.4% can be achieved, and we believe that the approach will offer even higher values in the future as a result of careful material selection.

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Figure 1: Photoluminescence spectra.
Figure 2: Transient photoluminescence characteristics.
Figure 3: Activation energy of reverse ISC rate.
Figure 4: Performance characteristics of the OLEDs with m-MTDATA:t-Bu-PBD emitting layer.
Figure 5: Formation of exciplex state between m-MTDATA and 3TPYMB.
Figure 6: Performance characteristics of the OLEDs with m-MTDATA:3TPYMB emitting layer.

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Acknowledgements

The authors thank K. Tokumaru for fruitful discussions. This work was supported in part by the Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST) and the Konica Minolta Science and Technology Foundation. The authors thank the Global Centers of Excellence (COE) programme ‘Science for Future Molecular Systems’ of the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT).

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Authors and Affiliations

  1. Center for Organic Photonics and Electronics Research (OPERA), and Center for Future Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan

    Kenichi Goushi, Kou Yoshida, Keigo Sato & Chihaya Adachi

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  1. Kenichi Goushi
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  2. Kou Yoshida
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Contributions

K.G. and K.Y. designed the experiments, carried out the measurements of the photoluminescence and electroluminescence characteristics and discussed the experimental data with C.A. K.S. provided experimental support and suggestions. K.G. and C.A. wrote the manuscript.

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Correspondence to Chihaya Adachi.

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Goushi, K., Yoshida, K., Sato, K. et al. Organic light-emitting diodes employing efficient reverse intersystem crossing for triplet-to-singlet state conversion. Nature Photon 6, 253–258 (2012). https://doi.org/10.1038/nphoton.2012.31

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